Circuit interrupter



April 26, 1932. j 5 MacNElLL 1,855,579

CIRCUIT INTERRUPTER Filed Dec. 15 1924 3 Sheets-Sheet l WITNESSES: INVENTOR ATTORNEY April 26, 1932. J MacNElLL 1,855,579

C IRGUI T INTERRUPTER Filed Dec. 15, 1924 3 Sheets-Sheet 2 WITNESSES: INVENTOR Patented Apr. 26, 1932 UNITEE STATES @FFICE JOHN B. MACNEILL, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & IJANUIACTURING COMPANY, A CORPORATION OF EENNSYLVANIA CIRCUIT INTERRUPTER Application filed December 15, 1924. Serial No. 755,858.

, bers for oil circuit breakers.

One object of my invention is to provide a circuit interrupter in which the final separation of contact members shall take place at high speed.

Another object of my invention is to provide a circuit interrupter in which the arcing contact members are restrained during the initial opening movement of the circuit interrupter in order to store energy for accelerating them during their final movement of separation.

A further obj ect of my invention is to provide a circuit interrupter in which the arcing contact members are restrained by the magnetic action of the electrical current traversing them during the initial opening movement of the circuit interrupter in order to store energy for their acceleration during their final movement of separation.

Figure 1 is a view in elevation of main and auxiliary contact members for a circuit interrupter embodying my invention,

Fig. 2 is an end view thereof,

Fig. 3 is a View, similar to Fig. 1, showing the relative position of the several parts at an intermediate stage in the opening operation of the circuit interrupter, and

Fig. 4 is a view, similar to Fig. 1, showing the relative position of the several constituout parts when the circuit interrupter is in the open position.

My invention comprises in general, a circuit interrupter 1 having a bridging member 2, that extends between main stationary con tact members 3 for the purpose of completing an electrical circuit, together with auxiliary or arcing contact members 4 and 5 that are mounted, respectively, on the bridging memher 2 and stationary contact members The auxiliary contact members 4 and 5 are for the purpose of makin the final interruption of electrical energy thereby preventing the pitting of the faces of the main contact members 3 and the bridging member 2. The bridging member 2 is supported by an operating rod 6.

The auxiliary contact members 4: are attached by screws 7 to arms 8 that are pivotally mounteo, as at 9, on the supporting rod 6. The arms 8 are each provided beyond their pivot points with an inwardly and downwardly extending lug 11 that is adapted to strike against the supporting rod 6 and act as a stop member, under conditions hereinafter described. A coil spring 12 is attached to an intermediate point on each of the arms 8 in order to bias them downwardly with respect to the bridging member 2.

Referring to Fig. 2, the under or lower surfaces 13 of the auxiliary contact member l are tapered downwardly or in a direction away from the coacting auxiliary contact members 5. The auxiliary contact members are in the form of spring pressed contact lingers or tips that converge in the direction of the auxiliary contact member 4. When the contact members l and 5 are in their closed positions, the contact members 5 pass over the widest portion of the contact member 4: and engage the tapered surfaces 13, thereby gripping the tapered surfaces.

Assuming the bridging member 2 to be in engagement with the stationary contact members 3 and that it is desired to open the circuit interrupter, the supporting rod 6 is depressed with a resultant movement of the bridging member 2 away from the stationary Contact members 3. Upon the separation of the bridging member 2 and the stationary contact members 3, he current is diverted through the auxiliary or arcing-contact members i and 5 which causes each set of contact members 5 to be attracted or drawn together by reason of the magnetic effect of the current traversing parallel paths in the same direction. The attraction of the contact members 5 increases the frictional engagement between them and the surfaces 13 of the auxiliary contact members a with the result that the auxiliary contact members l are held in substantially their original positions while the associated arms 8 turn about their pivots 9 and the springs 12 are placed under increasing tension.

By reason of the pivotal connection of the arms 8 to the supporting rod 6, the angular relation between the arms 8 and the supporting rod 6 varies during the separation of the bridging member 2 and the stationary contact members 3. Since the auxiliary contact members 4 are held between the contact members 5 during this movement, the engaging faces of the contact members 4 move relatively to the faces of the contact members 5 with a wiping action. The wiping action prevents the welding of the contact members 4 and 5 by avoiding a sustained concentration of current between the same increments of the engaging surfaces.

When the foregoing movement has continued until the lugs 11 engage the supporting rod 6, as shown in Fig. 3, further turning movement of the arms 8 is prevented and the auxiliary contact members 4 are drawn forcibly from between the contact members As soon as the auxiliary contact members 4 are freed from the contact members 5, their movement is accelerated downwardly by the springs 12 in addition to the continued clownward movement of the supporting rod 6 and bridging member 2, so that the iinal separation of current carrying members in the circuit interrupter 1 is accomplished at a very high speed. It is to be observed that when the auxiliary contact members 4 and 5 separate, the bridging member 2 and stationary contact members 3 have become so far separated that the danger of arc re-ignition therebetween is precluded. In order to again close the circuit interrupter, it is only necessary to move the supporting rod 6 upwardly and the parts return to their relative position, shown in Figs. 1 and 2.

With my improved arcing contacts, I am able to interrupt a very heavy current without danger of pitting the bridging member 2 and main contact members 8 and, at the same time, make the final separation take place within a relatively few cycles of an alternatin current.

It will thus be seen that I have provided a circuit interrupter in which the magnetic effect of the current traversing the auxiliary contact members is utilized to maintain them in engagement until the main contact members have separated a substantial distance, after which the auxiliary contact members are separated by a mechanical action and their final movement of separation if accelerated by springs placed under tension during the initial movement of separation.

In View of the foregoing and other obj ects of my invention, changes may be effected therein without departing from the spirit and scope thereof, as set forth in the appended claims.

I claim as my invention:

1. In a circuit interrupter, a pair of stationary main contact members, a bridging member, a supporting rod for the bridging member, an auxiliary stationary contact member co-operating with each main'contact member and co-operating auxiliary contact members pivotally mounted on the supporting rod, the pivoted auxiliary contact member being held by frictional engagement with the auxiliary stationary contact members during the initial separating movement of the bridging member and main stationary contact members, whereby the auxiliary contactmembers engage each other with a wiping action while being held in contact.

2. In a circuit interrupter, a pair of stationary main contact members, a bridging member, a supporting rod for the bridging member, an auxiliary stationary contact member co-operating with each main contact member and co-operating auxiliary contact members pivotally mounted on the supporting rod, the pivoted auxiliary contact members being held by frictional engagement with the auxiliary stationary contact members during the initial downward movement of the supporting rod, imparting a wiping action thereto while being held in contact.

3. In a circuit interrupter, a pair of stationary main contact members, a bridging member, a supporting rod for the bridging member, an auxiliary stationary contact member cooperating with each main contact member and cooperating auxiliary contact members pivotally mounted on the supporting rod, means adapted to bias said pivoted contact members away from said auxiliary contact members, the pivoted auxiliary contact members being held by the auxiliary stationary contact members during the initial separating movement of the bridging member and main stationary contact members.

In testimony whereof, I have hereunto subscribed my name this 9th day of December,

JOHN B. MAoNEILL. 

